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    SubjectRe: [PATCH] Gerd Hoffman's move-vsyscall-into-user-address-range patch
    Andrew Morton wrote:
    > Ingo Molnar <mingo@elte.hu> wrote:
    >
    >> * Andrew Morton <akpm@osdl.org> wrote:
    >>
    >>
    >>> Rusty Russell <rusty@rustcorp.com.au> wrote:
    >>>
    >>>> Name: Move vsyscall page out of fixmap into normal vma as per mmap
    >>>>
    >>> This causes mysterious hangs when starting init.
    >>>
    >>> Distro is RH FC1, running SysVinit-2.85-5.
    >>>
    >>> dmesg, sysrq-T and .config are at
    >>> http://www.zip.com.au/~akpm/linux/patches/stuff/log-vmm - nothing leaps
    >>> out.
    >>>
    >>> This is the second time recently when a patch has caused this machine
    >>> to oddly hang in init. It's possible that there's a bug of some form
    >>> in that version of init that we'll need to know about and take care of
    >>> in some fashion.
    >>>
    >> FC1 is like really ancient. I think there was a glibc bug that caused
    >> vsyscall related init hangs like that. To nevertheless let people run
    >> their old stuff there's a vdso=0 boot option in exec-shield.
    >>
    >>
    >
    > Well that patch took a machine from working to non-working. Pretty serious
    > stuff. We should get to the bottom of the problem so we can assess the
    > risk and impact, no?

    An easy test for culpability of kernel vs. init would be to back out all
    patches and recompile the kernel with vsyscall moved down by 4 megs.



    Index: linux-2.6.17-rc/include/asm-i386/fixmap.h
    ===================================================================
    --- linux-2.6.17-rc.orig/include/asm-i386/fixmap.h 2006-03-19 21:53:29.000000000 -0800
    +++ linux-2.6.17-rc/include/asm-i386/fixmap.h 2006-05-19 18:16:00.000000000 -0700
    @@ -20,7 +20,7 @@
    * Leave one empty page between vmalloc'ed areas and
    * the start of the fixmap.
    */
    -#define __FIXADDR_TOP 0xfffff000
    +#define __FIXADDR_TOP 0xffbff000

    #ifndef __ASSEMBLY__
    #include <linux/kernel.h>
    \
     
     \ /
      Last update: 2006-05-20 03:19    [W:0.022 / U:178.724 seconds]
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